okay, well this is geometry right? so you need to understand the use of sin, cos, and tan, do u get that? you can also solve it by using this formula. its easier and faster. Add the diagonals and times by 2

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these are properties of kites:
•Two pairs of adjacent sides of a kite are equal in length
•One pair of opposite angles (the ones that are between the sides of unequal length) are equal in size.
•One diagonal bisects the other.
•Diagonals intersect at right angles.